The rapid use of iron tools in the 6th century BCE enabled the villages to produce more cereals than what could be consumed within the village itself. The surplus produce was hence left to be sold in the market.
On the other hand, once cereals or food grains started to be produced in abundance, not all people required to stick to cultivation. They could now take up any other sort of activity to earn a living. Thus, there appeared a diversity of products on offer. This diversity and surplus production of goods enabled the establishment of trading links. Widespread contacts between villages and towns were now possible.
The wide use of money also facilitated the trading. Buying and selling of goods was no longer restricted within the boundaries of the country, international trading links too were established.